I already supported this idea but want to add a comment in order to raise the attention on this item.
The behaviour has changed I suppose in CVI2010 or 2012: up to 2009SP1 it was possible to edti the tab order of dimmed controls.
Up to 2013SP1 this facility is no more available.
It seems important to me to restore original behaviour: let's consider a complex UIR with several controls part of them dimmed to prevent user actions on some of them. At present, to change tab order you need to activate all dimmed controls, change the tab order and then redim previously dimmed controls: you may run the risk of forgetting to dim some control thus changing UI behaviour, possibly in a risky way.
